The last twenty years have seen unprecedented growth in both the type and demand for wireless communication services. Wireless voice communication services, including cellular telephone, Personal Communication Services (PCS), and similar systems now provide nearly ubiquitous coverage. The infrastructure for such networks has been built-out to the point where most residents of the United States, Europe, and other industrialized regions of the world have not just one, but multiple service providers from which to choose.
Continued growth in the electronics and computer industries increasingly contributes to demand for access to the Internet and the myriad of services and features that it provides. This proliferation in the use of computing equipment, especially that of the portable variety, including laptop computers, handheld Personal Digital Assistants (PDAs), Internet-enabled cellular telephones and like devices, has resulted in a corresponding increase in the need for wireless data access.
While the cellular telephone and PCS networks are widely deployed, these systems were not originally intended for carrying data traffic. Instead, these networks were designed to efficiently support continuous analog signals as compared to the burst mode digital communication protocols needed for Internet communications. Consider also that voice communication is adequate with a communication channel bandwidth of approximately 3 kilohertz (kHz). However, it is generally accepted that for effective Internet communication, such as for Web browsing, a data rate of at least 56 kilobits per second (kbps) or higher is required.
In addition, the very nature of the data traffic itself is different from the nature of voice communication. Voice requires a continuous duplex connection; that is, the user at one end of a connection expects to be able to transmit and receive to the user at the other end of a connection continuously, while at the same time the user at the other end is also able to transmit and receive. However, access to Web pages over the Internet is, in general, very burst oriented. Typically, the user of a remote client computer specifies the address of computer files such as on a Web server. This request is then formatted as a relatively short data message, typically less than a 1000 bytes in length. The other end of the connection, such as at a Web server in the network, then replies with the requested data file which may be from 10 kilobytes to several megabytes of text, image, audio, or video data. Because of delays inherent in the Internet itself, users often expect delays of at least several seconds or more before the requested content begins to be delivered to them. And then once that content is delivered, the user may spend several seconds or even minutes reviewing, reading the contents of the page before specifying the next page to be downloaded.
Furthermore, voice networks were built to support high mobility usage; that is, extreme lengths were taken to support highway speed type mobility to maintain connections as the users of voice based cellular and PCS networks travel at high speeds along a highway. However, the typical user of a laptop computer is relatively stationary, such as sitting at a desk. Thus, the cell-to-cell high speed mobility considered critical for wireless voice networks is typically not required for supporting data access.